cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A062691 Triangular numbers that contain exactly 2 different digits.

Table of values

n a(n)
1 10
2 15
3 21
4 28
5 36
6 45
7 78
8 91
9 171
10 300
11 595
12 990
13 1711
14 2211
15 3003
16 5050
17 5151
18 5565
19 5995
20 6555
21 8778
22 10011
23 66066
24 222111
25 255255
26 333336
27 500500
28 600060
29 828828
30 887778
31 1188111
32 5656566
33 22221111
34 50005000
35 51151555
36 88877778
37 2222211111
38 5000050000

List of values

[10, 15, 21, 28, 36, 45, 78, 91, 171, 300, 595, 990, 1711, 2211, 3003, 5050, 5151, 5565, 5995, 6555, 8778, 10011, 66066, 222111, 255255, 333336, 500500, 600060, 828828, 887778, 1188111, 5656566, 22221111, 50005000, 51151555, 88877778, 2222211111, 5000050000]

Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

Content is available under The OEIS End-User License Agreement.